High temperature lubrication process



Se t. 27, 1966 R. J. HOLZINGER ETAL 3,275,102

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' 61/06 0. Blake Afforney United States Patent 3 275 102 men TEMPERATURELUBRICATION PRocnss Rudolph J. Holzinger, Haddonfield, N-J., Lawton E.Reid, Kansas City, Mo., and Gilbert D. Blake, Overland Park, Kans.,assignors to Mobil Oil Corporation, a corporation of New York FiledSept. 11, 1963, Ser. No. 308,273 8 Claims. (Cl. 184-1) This invention isdirected to the use of water-in-oil emulsions for lubricating equipmentwhich must operate at ambient temperatures above 300 F. for extendedperiods of time and is particularly concerned with effective lubricationof oven conveyor chains.

In the manufacture of many products, there are involved various types ofmachinery which must operate at high temperatures. In commercialprocesses, such machinery is usually large and so expensive that continuous operation thereof is economically essential. Where there aremoving parts exposed more or less continuously to the prevailing hightemperatures, adequate lubrication with the proper lubricant is a primerequisite. In our application Serial No. 210,541, filed July 17, 1962,now Patent Number 3,213,024 of which this is a continuation-in-part, wehave described lubricant compositions comprising emulsions of water inlubricating oil which have proved to be outstandingly successful for useon machines operating at high temperatures, e.g., 300- 800 F. When suchemulsion compositions are applied the oil surrounding the droplets ofwater is deposited on the areas where lubrication is desired. At thesame time, the water in the emulsion is caused to flash off into steamdue to the high temperatures of the machinery and the steam generatedhas a blasting effect which serves to remove carbon, dirt and similardeposits which tend to accumulate on the hot moving parts.

Giant ovens have been developed for continuously conveying materialstherethrough which are generally about 100-300 ft. and up to 1000 ft. inlength and which utilize continuous chains travelling over sprocketwheels to convey the articles through the heating zone. These ovensoperate at approximately 300-800 F., depending upon the heat treatingconditions required. The heat is supplied by heated air or gas which iscirculated through the ovens by fans or blowers suitably located tomaintain uniform temperature throughout the oven. The conveyor chainsare continuous and usually contained substantially completely within theovens. However, even such parts as may be outside the oven are not farremoved therefrom and are still subjected to the high oven temperatures.The turbulence created by the circulating hot gas in the oven tends tocarry in suspension fine particles of dust, dirt, dried stucco, boardchips, fibers, and other particles from the product uridergoingtreatment which tend to deposit on the oil-wet chain links and rollers.Also, the oil used to lubricate the mechanism cracks at the hightemperature of the oven producing carbonaceous deposits on the chains.Carbonaceous deposits likewise result from decomposition of organicmaterials, such as resinous binders, coatings and the like. Theparticles become embedded in the carbonaceous material which acts as abinder and these deposits seriously increase the chain load, requiringadditional power to move the chain. These deposits can become so seriousthat they cause the chain links and rollers to freeze and may even causethe chain to buckle and break.

Current practice calls for application of lubricants to hot ovenconveyors or the like by gravity feed. With the conventional typelubricants, this is generally unsatisfactory in that the oil may tend tovaporize prema- Patented Sept. 27, 1966 turely and prevent adequatelubrication and/or cause carbon build-up on the conveyors. Even with thewaterin-oil emulsion lubricants disclosed in our prior application, ifgravity feed is used, care must be exercised to prevent excessivepremature loss of water before the lubricant actually contacts the partsto be lubricated.

It is an object of this invention to provide a process for applying awater-in-oil emulsion lubricant to a hot surface to be lubricated.

It is a further object to apply a lubricant to equipment operating forsustained periods of time at temperatures of 300800 F.

It is another object of this invention to lubricate conveyor chains andother moving elements in dusty ovens operating at temperatures of over300 F.

It is yet another object to provide means for cleaning and lubricatingmoving elements while such elements are operating at high temperaturesfor sustained periods of time.

These and still other objects. and advantages of the present inventionwill be more fully disclosed in the drawings annexed hereto and in thedetailed description of the invention set forth hereinafter.

In the drawings:

FIGURE 1 represents a diagrammatic view, in elevation, of one form ofthe invention; and

FIGURE 2 represents a diagrammatic view, partly in elevation and partlyin section, of another form of the invention.

In accordance with one aspect of this invention, moving mechanismsoperating at ambient temperatures above 300 F. are effectivelylubricated by applying a water-inoil emulsion lubricant composition tothe mechanisms while the lubricant is still in the form of an emulsionat the time of contact with the mechanisms, the lubricant emulsionhaving been maintained, prior to such contact, at a temperature andpressure sufiicient to keep the water in the emulsion in liquid form. Inthe lubrication of moving parts in a high-temperature oven, forinstance, the feed lines which carry the lubricant to the points oflubrication must, at least partially, be located inside the oven. Otherparts of the lubricating system are in close proximity to the oven wheretemperatures tend to exceed the boiling point of water. As aconsequence, water will be prematurely and undesirably lost from thewater-in-oil lubricant emulsion and, in addition, vapor lock of the feedlines may be caused. The present invention serves to avoid theseobjectionable difiiculties.

As shown in FIGURE 1, the invention is applied to an oven 1 with movingmechanisms 2, to be lubricated. Passing through a wall of the oven,there is provided one or more lubricant feed lines 3 carrying presusrerelief valves 5 and lubricating nozzles 6 at the oven ends of such feedlines 3. The other endsof the feed lines are connected to manifold 7which is supplied by feed line 8 from pump-9. Lubricant from a suitablesupply source is carried to pump 9 through line 10. The pump is drivenby a suitable power source such as electric motor 11, driven by powersupplied through timer switch 12.

In operation, a water-in-oil emulsion lubricant is supplied,successively through line 10, pump 9, line 8, manifold 7, lines 3,pressure relief valves 5 and nozzles 6 to mechanisms 2 in oven 1,thereby lubricating such mechanisms.' The pressure relief valves 5 areset for a pressure slightly higher than that necessary to maintain thewater in the lubricant emulsion in liquid form at the temperaturesencountered in the oven 1. Thus, at an oven temperature of 450 F., thevapor pressure of water is 422.6 p.s.i.a., and the lubricant ismaintained at a pressure slightly above that point, e.g., 450-500 p.s.i.Under these conditions, with relief valves 5 set for about 475p.s.i.,and

with pump 9 being capable of delivering the lubricant at about500p.s.i., timing device 12 is activated to operate motor, 11 and connectedpump 9 to deliver lubricant at periodic intervals under pressures ofabout 500 p.s.i., sufficient to overcome the setting of relief valves 5.This sequence of operations serves to supply the lubricant to themechanisms in adequate quantities without premature loss of water fromthe lubricant emulsion. Of course, if desired, the pump 9 may beoperated continuously to supply a steady stream of lubricant to themechanisms.

In the preferred construction, nozzles 6 have somewhat larger.innerdiameters than those of feed lines 3. This serves to provide moreeffective relief of pressure than would otherwise be the case andjetting or spraying of the lubricant is avoided. It is also preferredthat the lengths of nozzles 6 be kept to the minimum consonant withadequate lubrication without volatilization so that the lubricant isapplied to the mechanisms in the form of a substantially uniformemulsion.

When using .a pump. to deliver the lubricant as show in FIGURE 1, it mayoften be desirable to keep it running continuously rather thanintermittently. This can be done by using a closed hydraulic circuit,with a valve (not shown) located in thehigh pressure leg and actuated bya timer which will release a fixed amount of lubricant at predeterminedintervals into the manifold. Such an arrangement would also providecontinuous homogenization of the emulsion if normal operation isinterrupted.

It should also be noted that the feed lines and other elements in thislubricating system, which operate in the hot ovens or closely adjacentthereto, should be as short as possible to minimize heat transfer to theemulsion lubricant. If desired, the temperatures of these feed lines andthe like, may be controlled by applying heat insulation thereto, by useof coolant in a surrounding jacket, or by combinations thereof, asindicated, diagrammatically in dotted lines by 50 in FIGURE 1, withrespect to a single feed line. to all elements which require thisprotection from exposure to the extremely high temperatures prevailing.A system for such temperature control is shown in greater detail inFIGURE 2, wherein similar numbers represents parts similar to thoseshown in FIGURE 1.1

As shown in FIGURE 2, oven 1 with moving mechanisms 2 therein, isprovided withfeed line 23 passing througha wall of the oven. Feed line23 is surrounded by a cooling jacket 24 and outer layer or jacket'25which may be in the form of high-temperature insulation or a closedjacket containing air or other inert heat insulating gas. Cooling jacket24 is furnished with inlet conduit 26 and outlet conduit 27, which isattached to pump 28. A

heat exchanger 29 is connected to pump. 28 through 0011 duit 30 and alsoto jacket 24 through conduit 26. 7

According to the modifications shown in FIGURE 2, a water-in-oillubricant is; supplied under relatively low pressure, static or pump, tofeed conduit 23 passing through (cooling jacket 24 and thence tomechanisms 2 which are .lubricated thereby. Coolant fiuid in jacket.

24 keeps the temperature of the lubricant in line; 23 from risinglabovethe critical temperature of the water contained therein. The coolantfluid may be any one of the many available heat transfer fluids,preferably one. that does notboil at the temperatures prevailing theoven or the like since one may thus avoid thenecessity for use of highpressure conduits which would otherwise be re-;

quired to prevent rupture of the conduits in the event of failure ofcirculation. Coolant fluid passes through outlet conduit 27 and pump28to a heat exchanger 29 i through conduit 30. Heat exchanger 29 lowersthe temperature of the hot coolant fluid to the desired point and thecooled fluid is then returned to jacket 24 through feed conduit 26. Thelubricant may be supplied to the system at pressures just sufiicientlyabove atmospheric to ensure adequate flow to the point where lubricationis desired.

In practice, such expedients could be applied to the mechanisms to belubricated as in FIGURE'Z,

may be close to atmospheric .and with adequate cooling, the pressure ofthe lubricant is not substantially above atmospheric. If it is desiredto reduce the amount of cooling and operate at higher temperatures,slightly higher pressures should prevail in the lubricant feed linesinsuch event, onemay use a pressure relief valve, indicateddiagrammatically in dotted lines by 55,1 which operates in substantiallythe same manner assimilar valves 5 in FIGURE 1. More specifically, 'thelubricant can be maintained at an intermediate temperature of 250 F. byproper control of the coolant fluid temperature. At 250 F., a lubricantsystem pressure of 30 p.s.i.a. would contain the water within theemulsion. The pressure relief valve set to operate at pressures slightlyabove 30 p.s.i.a. would be effective. Whether or not a relief .valve isused, it remains. desirable to apply the lubricant to the mechanisms assoon as possible after its issuance from the point of temperature andpressure control. As pointed out in connection with FIGURE 1, it isdesirable. to prevent jet or spray discharge of the lubricant. As afurther. modification of the system shown in FIGURE 2, the lubricantbefore being fed into the supply conduit 23, "may be refrigerated byjanysuitable means and the need for cooling would be accordingly reduced,particularly if the feed lines are efiiciently insulated.Prerefrigeration of the lubricant supply to the pump 9 in FIGURE 1 wouldalso be effective in reducing the pressures required for maintenance ofthe water in liquid form.

As described above, according to the present invention, the pressure andtemperature. of the lubricant are controlled so that the emulsion canreach the surfaces to be lubricated withoutjsubstantial, loss of water,Thus, the lubricant is applied as a liquid rather than a mist permittingit to penetrate in, unaltered form.. Subsequent intimate contact withhot metal, in addition to providing lubrication, provides steam cleaningaction to control deposits originating from the material being processedor decomposition of the lubricant, or both. Because the water isvaporized on contact, the steam acts as a snuffer andstack fires areeliminated. Use of our lubrication method with our novel lubricantsgreatly minimizes formation of carbon or other deposits. Such depositsas may be formed contain numerous small gas pockets caused by theexpanding steam, imparting a friable consistency to such deposits sothat they are ing mechanisms itself, without need of other means ofremoval. 'These results serve to increase the life and usefulness of thelubricated jmechanisms while at the same time decrease powerrequirements significantly.

The water-in-oilemulsions used inthe present invention are described ingreat detail in our application Serial No. 210,541. Broadly, theseemulsion lubricants comprise about 0.1 to 5.0 percent, by weight,sufli'cientto emulsify the water and oil, of an emulsifier, about 0.1

to 5.0 percent, by weight, of a high-temperature stabilizer for saidemulsion, the combined emulsifier. and stabilizer having -an;-HLB(hydrophilic-lipophilicjbalance) number ofabout 2-8, the oil portion ofsaid emulsion being a hydrocarbon oil of from about. 50- 1000 SUSviscosity at F. in the amount of about '85-30 percent, by weight, thewater content of said emulsion beingl5-70 percent, by weight, and about0.05 to 5.0 percent, by weight, of a solid lubricant in :finely dividedform. It is obvious that any of the lubricants set forth in thatapplication may be used under the present invention. I Variousmodifications and changes other than those set forth above may'beresorted to without departing from the spirit and scope of theinvention. Such variations and modifications are considered to be withinthe scope of the appended claims.

What is claimed is:

1. In a process for applying Water-in-oil emulsion lubricants to hotmoving mechanisms operating within a heated zone at ambient temperaturesabove about 300 F., the steps comprising:

(1) conveying the emulsion lubricant to and into the said heated zone;

(2) maintaining the said emulsion lubnicant in an emulsified state undersuch temperature and pressure conditions as to prevent conversion of thewater in the emulsion lubricant into steam prior to its application; and

(3) directing said emulsion lubricant in an exposed steam through saidheated zone toward the hot moving mechanism, contact therewith causingthe water to evaporate on the surface of the said mechanism, whereby thesaid evaporation cools and cleans the surface of the said mechanism andleaves a deposit of oil on the said surface.

2. The process of claim 1 in which the emulsion lubricant is maintainedat a pressure slightly above atmosphenic and at a temperature below thecritical temperature of water at that pressure.

3. The process of claim 1 wherein the ambient temperatures in the heatedzone range from about 300 to about 800 F.

4. The process of claim 1 wherein the pressure temperature of the heatedzone is about 450 F. and the 6 lubricant in step 2 is maintained at apressure of about 450 to 500 p.s.i.a.

5. The process of claim 1 in which the lubricant is maintained at atemperature of about 250 F. and at a pressure of about 30 p.s.i.a. untilit is applied to the mechanism.

6. The process of claim 1 wherein the heated zone is an oven.

7. The process of claim 1 wherein the hot moving mechanism is an ovenconveyor mechanism.

8. The process of claim 1 wherein the emulsion lubricant contains byweight of total emulsion: from about 0.1% to about 5% of an emulsifier,from about 0.1% to about 5% of a high temperature stabilizer for saidemulsion, the combined emulsifier and stabilizer having ahydrophilic-lipophilic balance number of from about 2 to about 8; about85% to about 30% of a hydrocarbon oil having an SUS. viscosity at 100 F.of about to 1000, and about 15% to about 'of water and about 0.05% toabout 5.% of a solid lubricant in finely divided form.

References Cited by the Examiner UNITED STATES PATENTS 2,664,173 12/1953Korig 184-104 2,794,681 6/1957 Suess 239132 3,074,648 1/1963 Stone239-132 LAVERNE D. GEIGER, Primary Examiner.

CLINE, E. EARLS, Assistant Examiner.

1. IN A PROCESS FOR APPLYING WATER-IN-OIL EMULSION LUBRICANTS TO HOTMOVING MECHANISMS OPERATING WITHIN A HEATED ZONE AT AMBIENT TEMPERATUREABOVE ABOUT 300*F., THE STEPS COMPRISING: (1) CONVEYING THE EMULSIONLUBRICANT TO AND INTO THE SAID HEATED ZONE; (2) MAINTAINING THE SAIDEMULSION LUBRICANT IN AN EMULSIFIED STATE UNDER SUCH TEMPERATURE ANDPRESSURE CONDITIONS AS TO PREVENT CONVERSION OF THE WATER IN THEEMULSION LUBRICANT INTO STEAM PRIOR TO ITS APPLICATION; AND (3)DIRECTING SAID EMULSION LUBRICANT IN AN EXPOSED STEAM THROUGH SAIDHEATED ZONE TOWARD THE HOT MOVING MECHANISM, CONTACT THEREWITH CAUSINGTHE WATER TO EVAPORATE ON THE SURFACE OF THE SAID MECHANISM, WHEREBY THESAID EVAPORATION COOLS AND CLEANS THE SURFACE OF THE SAID MECHANISM ANDLEAVES A DEPOSIT OF OIL ON THE SAID SURFACE.